The present invention relates to liquid and gas contact apparatus for heat transfer and mass transfer apparatus. More specifically, the invention relates to the heat and mass transfer media, or film fill-pack, utilized within the cooling tower as a liquid-to-gas contact apparatus to cool a heat-transfer fluid. The heat and mass transfer media, or fill-pack, material is generally vertically oriented with fluid coursing over the material and an air stream is transversely directed through the loosely nested or spaced fill-pack material to interact with the fluid for heat and mass transfer. The fill-pack material generally provides a structural apparatus inhibiting the rate of fluid flow between a fluid-feeding device at the upper portion of the tower to a sump at its lower level, which inhibited fluid-flow rate increases the contact time between the fluid and the transversely moving air or gas.
The control or inhibition of the liquid flow rate to increase the contact time with flowing gas or fluid may be considered liquid management as a reference term.
Various structures, materials and physical arrangements have been provided in an attempt to enhance the interaction between the gas or air and the fluid in fill-pack materials. This would promote the efficiency of the heat and mass transfer operation and thus the efficiency of heat and mass transfer devices, such as cooling towers. The thermal efficiency of a cooling tower is related to the mass of air flowing through the tower, the fluid-air interface per unit of fluid flowing through the tower, and also to the degree of turbulence of the flow of air and water adjacent to the interface. An attempt to accommodate a greater interaction between the air and fluid, and thus to increase the tower efficiency, is noted in U.S. Pat. No. 3,286,999 to Takeda. In this structure, alternative arrangements of corrugated ribbing in bands across the fill sheet are illustrated, that is with or without transverse blank strips, but both arrangements have hollow projections extending above the corrugated surfaces. The sheet material may be a polyvinyl chloride with a specified band width and groove inclination. A binder secures rice powder to the fill-sheet surfaces. It is asserted that the rice, or other material, acts as a wetting agent to spread the water on the face of the sheets. In addition, enhancement of the surface wetting is proposed by the addition of a surfactant to the water.
U.S. Pat. No. 4,548,766 to Kinney, Jr. et al. discloses a formed fill sheet for crossflow water cooling towers, which fill sheet has a repeating chevron pattern with the ridges on one sheet face defining the grooves on the other face. An improvement in the heat transfer is attributed to the angularity of the ridge sections with respect to each other, the vertical height of the pattern, the transverse angulartiy of the ridges and the spacing between the adjacent sheets. W-shaped spacers projecting in opposite directions from each of the sheets have complementary notches to receive the foot portions of the spacer to maintain adjacent sheets in required horizontally spaced relationships. These spacers are angled to provide minimum air-flow interference. The chevron shaped pattern repeats itself in alternating rows of angled ridges and grooves. However, there are circular grooves arranged along upright lines at opposite sides of the sheet and are operable as knockouts for receipt of supports bars. The use of the w-shaped spacers is asserted to aid assembly of the fill pack at the tower site by the avoidance of requisite gluing of the fill material.
U.S. Pat. No. 3,599,943 to Munters teaches a contact fill-material product with a corrugated structure of pleats or folds. The contact fill-materials are vertically positioned thin layers or sheets formed with pleats crossing each other in adjacent layers. The layers may be cellulose or asbestos impregnated with a stiffening or strengthening substance, such as a resin. The crossing pleats bear against each other to form channels with continuously varying widths both vertically and horizontally. This is purported to enhance air to water contact to more effectively cool the water. A similar glued together section of fill material is illustrated in U.S. Pat. No. 3,395,903 to Norback et al. The corrugated sheets of the material have the corrugations at an angle with the sheets joined together at their edges and providing channels between the corrugated layers.
A thin-sheet fill material with zigzag-shaped corrugations, which are bent transverse to its plane along a plurality of lines transverse to the corrugations, is shown in U.S. Pat. No. 3,540,702. A plurality of the sheets are joined back to back so that the bent portions of adjacent plates extend in opposite directions to form large flow passages for gas with the corrugations foring flow passages for a liquid.
Another illustration of an angularly grooved and corrugated fill sheet is taught in U.S. Pat. No. 4,361,426 to Carter et al. The angularly grooved fill material is spaced, horizontally extending, corrugated and vertically oriented with its surface enhanced by molded-in angular zigzag grooves. This material increases the exposed wetted surface area of the fill and causes turbulence of air in the passageways between the fill sheets. The purpose of the enhanced flow and surface areas was to increase air and water contact time to increase the thermal performance of the fill material.
A serpentine fill packing material is disclosed in U.S. Pat. No. 4,518,544 to Carter et al., which fill material is composed of individual side-by-side sheets having serpentine or sinusoidal shapes with crests or ridges. Adjacent sheets have the sinusoidal shapes in directly opposite paths. The sheets are supported or maintained in place by a spacing knob male locator on a ridge of any sheet and a spacing socket female locator within a valley of any sheet. The groove width constantly varies at a ridge or a valley from the bottom to the top edge. The sidewall angle of the groove relative to the perpendicular to the plane of the sheet is a constant angle at any position in the fill groove sheet height.
U.S. Pat. No. 4,801,410 to Kinney, Jr. et al. provides a vacuum formed fill sheet with spacing elements to maintain spacing about the perimeter and interior of the sheet. The individual fill-sheet pack are formed in a corrugated pattern with the peaks and valleys of adjacent sheets being inclined in opposite directions to maintain sheet spacing. Honeycomb structure formed along the facing and side edges of adjacent sheets assist in the maintenance of sheet spacing.
U.S. Pat. No. 5,722,258 to Aitken illustrates a fill package having corrugated metal elements arranged with vertical passages between adjacent elements. Perforations are provided in the corrugated sections of the fill material. The corrugations in each section extend at an angle to the horizontal. It is asserted in the disclosure that the corrugations function as fins to increase the heat transfer area.